The correct answer is (C) 4.5 billion years
Radioisotopes can be defined as the isotopes made of radioactive atoms. They break continually till they form a material that is stable in atmosphere. By seeing how radioisotopes breakdown and the amount of radioactive materials found in the fossils, geologists can determine the age of rocks. Scientist discovered the oldest known rock whose age is determined 4.37 billion years old. This was determined using radioisotopes. The earth might be older than this but according to radioisotopes the age of earth is around 4.37 or 4.5 billion years old.
